nosquirrel,
My only suggestion to your itinerary would be to Cuzco (CUZ) to your itinerary after LIM.
There ain't a whole lot to see in Lima when you compare to the "ruins" in Cuzco. A round trip ticket on some of the Peruvian domestic airlines costs between $150 to $250 USD.
LAN Peru (a subsidiary of Lan Chile a OneWorld Alliance member) will qualify you for miles (roughly 500 each way because it's the minimum if I recall). And I don't recall LAN Peru being too much more $$$ wise.
Enjoy the trip, I'm envious.
Tizoc
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Travel light, travel cheap, travel often